COMBAT OUTPOST GARDA, WARDAK PROVINCE — Increasingly, coalition troops feel they cannot trust the Afghan soldiers and police with whom they live and serve. The increasing toll of “green-on-blue” killings drives a wedge of mistrust deeper between foreign and Afghan forces and they also cause the American public to question why Washington is helping the Afghan government and military at all. And these doubts and questions are critical because, in order for the U.S. to declare any kind of victory after the 2014 withdrawal, it has to train and mentor a viable Afghan security force that will respect human rights and prevent a much-feared civil war or Taliban takeover.